| Co-Investigator(Kenkyū-buntansha) |
NISHITANI Nozomu Solar-Terrestrial Enviroment Lab., Nagoya University Res.Associate, 太陽地球環境研究所, 助手 (10218159)
NAKAMURA Rumi Solar-Terrestrial Enviroment Lab., Nagoya University, Res.Associate, 太陽地球環境研究所, 助手 (90252296)
FUJII Ryoichi Solar-Terrestrial Enviroment Lab., Nagoya University Professor, 太陽地球環境研究所, 教授 (00132712)
OGINO Tatsuki Solar-Terrestrial Enviroment Lab., Nagoya University Professor, 太陽地球環境研究所, 教授 (00109274)
KOKUBUN Susumu Solar-Terrestrial Enviroment Lab., Nagoya University Professor, 太陽地球環境研究所, 教授 (00011502)
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| Research Abstract |
On the basis of satellite/ground-based data combined with computer simulations, this research examines :
1. What is the solar wind/interplanetary magnetic field parameter best determines occurrence and the intensity of geomagnetic storms?
2. Is a magnetic storm a simple result of the frequent occurrence of intense substorms?
It uses, in addition to solar wind/interplanetary magnetic field data, the standard Dst and AL indices, the equatorward boundary of the auroral belt determined form auroral particle precipitation(i, e., the size of the polar cap), plasma and field data from the Geotail satellite, and also relies strongly on MHD three-dimensional code of solar wind/magnetosphere coupling that is for the purpose of quantitative evaluation of energy flow associated with geomagnetic storms. Information on ring current constituents derived from the AMPTE and CRRES spacecraft is also referred to. The following are the main findings :
1. Different from earlier statistical studies, such as Sugiura and Chapman and Taylor et al., the main phase of major magnetic storms goes through a two-step growth. This implies that not only the injection rate of ring current particies but also the decay rate of the ring current is important in determining the intensity of maqnetic storms.
2. The magnetotail pressure (=magnetic pressure and plasma pressure) becomes very high during the main phase of magnetic storms. It reaches often ten times larger than its quiet-time value, that cannot be accounted for by an increase in the solar wind dynamic pressure.
3. During the main phase of large storms, the ionospheric ion component becomes dominant, indicating that substorm occurrence is important in the main phase.
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